1. Field of Invention
The present invention relates generally to folding paperboard cartons, and more particularly to an improved carton blank for use in assembling a carton having an improved appearance and improved security.
2. Brief Description of the Prior Art
Folding cartons are well known in the packaging art. These cartons are constructed from flat blanks which are pre-cut and pre-scored on paperboard sheets. Carton blanks have four main panels which are adapted to form the top, rear, bottom and front of an assembled carton. Each panel has a pair of end flaps which are hingedly connected by score lines formed in the paperboard.
The blanks are folded once and secured with known adhesives to form carton sleeves which are used for packaging retail products, typically consumable goods. During the filling operation, packaging machinery is used to form and seal fully assembled cartons according to a prescribed folding sequence and adhesive pattern.
U.S. Pat. No. 4,712,730 describes a state-of-the-art carton blank used to assemble a rectangular, top opening carton. First and second ends of the carton are closed by folding the bottom panel end flaps first; front panel end flaps second; top panel end flaps third and rear panel end flaps fourth and last.
Prior to folding in the fourth down flap, single lines of adhesive are deposited on the bottom panel end flaps. All four end flaps are secured by single glue lines to form a smooth, continuous wall at first and second ends of the carton. Commercial products of the type described in U.S. Pat. No. 4,712,730 are manufactured and sold by Fold-Pak Corporation, Newark, N.Y. under the HI TECH.RTM. trade designation.
According to art-recognized techniques, adhesive attachment of the end-wall forming flaps is difficult to achieve because overlapping end flaps are not co-planar in the folded condition. In specific terms, first-folded bottom panel end flaps are spatially removed from fourth-folded rear panel end flaps by intervening front and top panel end flaps. This spatial separation is generally characterized by a single or double thickness of paperboard stock.
U.S. Pat. No. 4,872,609 addresses this problem by describing raised portions formed in the bottom panel end flaps of a typical carton blank. These raised portions are substantially triangular in shape and operably associated with cutouts formed in the front panel end flaps of an assembled carton. According to this disclosure, the end wall-forming flaps are substantially co-planar so that fourth-folded rear panel end flaps are securely fastened to first-folded bottom panel end flaps with known adhesive patterns.
Carton blanks are typically produced on large paperboard sheets in a multiple configuration. Individual blanks are internally "nested" on three sides to minimize the amount of excess or wasted paperboard. During the blanking operation, score lines are provided to facilitate the flap-folding sequence. Perforations are also cut in the paperboard to form art-recognized tear-away and breakaway features like those described in U.S. Pat. No. 4,712,689. Perforations and score lines are formed by die-cutting and die-stamping the carton blanks in a single, downward direction.
The offset portions of the prior art are raised from the bottom panel end flaps of a carton blank. They are formed in the paperboard stock by stamping the carton blanks in an upward, opposite direction with reference to the score lines and perforations. This procedure involves a reverse die-stamping operation which requires special make ready procedures and additional expense. In addition, it may be difficult to effect a reliable seal between the rear flap and the front panel end flaps, thereby creating the possibility of unwanted leakage of semi-solid product from the package.